JPH0781628B2 - Line pressure control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a line pressure control device for an automatic transmission, and more particularly to a device for appropriately controlling the line pressure during gear shifting.

(Prior Art) An automatic transmission has various friction elements (clutch, brake, etc.) of a speed change gear mechanism, which are selectively hydraulically actuated by line pressure to select a predetermined shift speed and change the actuating friction element. Shift to the gear position of.

For this reason, if the line pressure is too high, the transitional engagement capacity of the friction element becomes excessive and a large shift shock occurs, and if the line pressure is too low, the transitional engagement capacity of the friction element becomes too small and the friction element slips. As a result, the service life is shortened. Therefore, it is necessary to properly control the line pressure. In the past, for example, as described in "Automatic Transmission RE4R01A Type Maintenance Manual" (A261C07) issued by Nissan Motor Co., Ltd. in March 1987, it can be said that shifting is in progress or non-shifting. Therefore, the line pressure is controlled by determining the drive duty of the line pressure control solenoid based on the engine throttle opening from the different table data.

However, in such a conventional line pressure control device, when the line pressure control solenoid has product variations or when the characteristics change over time, or when the friction elements have product variations, the friction material ages. When a change occurs, in the former case the line pressure deviates from the proper value even with the same solenoid drive duty, and in the latter case the line pressure is not the proper value for the friction element even if it is controlled as intended. However, there is a risk of gear shift shock and shortening of the life of friction elements due to excess or deficiency of the line pressure.

By the way, as shown in FIG. 10, for example, a case where the automatic transmission of the above document shifts from the ON state to the OFF state of the shift solenoid at an instant t ₁ due to a decrease in the engine throttle opening degree to shift up from the first speed to the second speed is considered. When the line pressure is low, the 2nd speed selective pressure with this as the source pressure rises as shown by the solid line and the corresponding friction element is engaged and advanced, and the input / output speed ratio N _T / N of the transmission gear mechanism is increased. _The gear ratio represented by _O (N _T : input speed, N _O : output speed) changes from the first speed equivalent value to the second speed equivalent value as shown by the solid line, and the transmission output torque becomes as shown by the solid line. On the other hand, when the line pressure is high, the operation waveform is as shown by the dotted line. Therefore, from the time during which the gear ratio N _T / N _O is changing, that is, the inertia phase time T, it is possible to determine whether or not the line pressure is an appropriate value in consideration of the above-mentioned variations and changes over time. From this point of view, the present applicant previously described in Japanese Patent Application No. 62-327452 the input rotation speed and output rotation speed of the transmission gear of the automatic transmission described above,
The input rotation sensor and the output rotation sensor respectively detect, and based on the signals from these sensors, the inertia phase time measuring means measures the time during which the gear ratio represented by the ratio between the input and output rotation speeds is changing. However, the line pressure adjusting means has proposed a line pressure control device for controlling the line pressure during the gear shift so that the inertia phase time becomes a target value, and according to such a device, the actual situation of the automatic transmission is constantly improved. It is possible to perform a suitable line pressure control, and it is possible to avoid a large shift shock and a reduction in the life of the friction element due to excess or deficiency of the line pressure.

(Problems to be Solved by the Invention) The inventors of the present application, however, have found the following improvements while further researching the above device.

That is, for example, when performing the upshift gear shift shown in FIG. 10, when the line pressure is extremely low, the rising portion of the selective pressure, that is, the so-called shelf portion is too low as a whole as shown by the chain line in the figure, and the friction element is engaged. Delay, the selective pressure rises sharply at the end of the shelf part due to the end of the stroke of the gearshift shock prevention accumulator, so the friction element is rapidly engaged, so the inertia phase ends after the end of the accumulator stroke. The shift shock may become extremely large due to an out-of-shelf shift.

However, in the above-mentioned device, even if the line pressure is low enough to cause such an out-of-shelf shift, the inertia phase time is short, so learning control is performed to further reduce the line pressure. It was impossible to completely eliminate the possibility that out-of-shifting could not be avoided, and therefore a large shift shock would occur and the life of the friction element would be shortened.

The present invention provides an apparatus that advantageously eliminates such improvements.

(Means for Solving the Problems) As shown in FIG. 1, a line pressure control device for an automatic transmission according to the present invention selectively hydraulically operates various friction elements of a speed change gear mechanism by line pressure so that a predetermined speed is established. Corresponding to the line pressure of an accumulator provided in at least one of hydraulic circuits that guides the line pressure to the various friction elements while changing the friction element to be operated to change the speed to another gear stage. The input rotation sensor and the output rotation sensor respectively detect the input rotation speed and the output rotation speed of the transmission gear mechanism of the automatic transmission in which the hydraulic pressure of the hydraulic circuit is slowly increased by the stroke based on the back pressure. , The inertia phase time measuring means changes the gear ratio represented by the ratio between the input and output speeds based on the signals from these sensors. In the line pressure control device, the line pressure adjusting means controls the line pressure during the shift so that the inertial phase time is measured so that the inertia phase time becomes a target value for preventing shift shock. An inertia phase pre-start time measuring means for measuring the inertia phase pre-start time from the instruction to change the gear ratio from the instruction to change the element, and the inertia phase pre-start time is the inertia phase after the end of the stroke of the accumulator. When the reference value for determining the out-of-shelf shift for terminating the shift is exceeded, the line pressure adjusting means is caused to perform control for increasing the line pressure during the shift by a predetermined amount regardless of the inertia phase time. The out-of-shelf shift avoiding means is provided.

(Operation) In such a device, the transmission gear mechanism selectively hydraulically operates various friction elements by the line pressure to select a predetermined shift speed, and the supply power is increased / decreased and output at this shift speed. Then, the transmission gear mechanism is shifted to another shift stage by changing a friction element that is hydraulically operated, and an accumulator for gear shift shock prevention provided in at least one of hydraulic circuits that guides line pressure to various friction elements, A stroke is made based on the back pressure corresponding to the line pressure to slowly increase the hydraulic pressure in the hydraulic circuit.

During this shift, the input rotation sensor and the output rotation sensor detect the input rotation speed and the output rotation speed of the transmission gear mechanism, respectively, and the inertia phase time measuring means determines the transmission gear mechanism based on the signals from both sensors. Measure the time of the inertia phase during which the gear ratio, which is represented by the ratio between the input and output speeds, changes. Then, the line pressure adjusting means controls the line pressure during the shift so that the inertia phase time becomes a target value for preventing the shift shock.

On the other hand, the means for measuring the time before the start of the inertia phase is
The time before the start of the inertia phase from the instruction to change the friction element until the gear ratio starts to change is measured, and the out-of-shelf gear shift avoiding means starts the inertia phase after the end of the accumulator stroke. If the value exceeds the reference value for determining the out-of-shelf speed change to be completed, that is, if the friction element starts to be engaged too late, an out-of-shelf speed change may have occurred. The line pressure adjusting means is controlled to increase the line pressure during the shift by a predetermined amount regardless of the inertia phase time in the shift.

Therefore, according to this device, even if there is product variation in the line pressure control element or characteristics change over time, or if there is product variation in the friction element or friction material change over time, these It is possible to perform line pressure control that takes into account individual differences and changes over time in automatic transmissions, and it is possible to avoid the occurrence of a large shift shock and the reduction in the life of friction elements due to excess or deficiency of the line pressure, as well as the shelf. When shifting is performed at a low line pressure that causes out-of-shift shifting,
Since the line pressure adjusting means is controlled to increase the line pressure by a predetermined amount regardless of the inertia phase time at the time of shifting at the low line pressure, the line pressure during shifting can be promptly increased, and it can be removed from the shelves. It is possible to effectively avoid gear shifting and reliably prevent occurrence of a large gear shifting shock and reduction in the life of the friction element.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 2 shows a power train control system of an automobile incorporating a device of an embodiment of a line pressure control device of the present invention, 1 is an electronically controlled fuel injection engine, 2 is an automatic transmission, 3 is a differential gear, and 4 is a drive. The wheels.

The engine 1 includes an engine control computer 5, which includes a signal from an engine rotation sensor 6 for detecting an engine speed N _E , a signal from a vehicle speed sensor 7 for detecting a vehicle speed V, and an engine throttle opening TH. The signal from the throttle sensor 8 for detecting, the signal from the intake air amount sensor 9 for detecting the engine intake air amount Q, etc. are input. The computer 5 determines the fuel injection pulse width T _P based on these input information and commands it to the engine 1, or supplies an ignition timing control signal (not shown) to the engine 1. The engine 1 is supplied with an amount of fuel according to the fuel injection pulse width T _P, and operates by burning this fuel in synchronism with the rotation of the engine.

Further, the automatic transmission 2 includes a torque converter 10 and a speed change gear mechanism 11 in tandem, and inputs engine power to the input shaft 12 via the torque converter 10. The input rotation of the transmission to the shaft 12 is accelerated and decelerated according to the selected gear of the transmission gear mechanism 11 to reach the output shaft 1, from which the drive gear 4 is passed through the differential gear 3 to drive the vehicle. it can.

Here, the speed change gear mechanism 11 incorporates various friction elements (not shown) such as clutches and brakes that determine the transmission path (gear stage) from the input shaft 12 to the output shaft 13, and the line pressure P of these various friction elements is set. It is assumed that the hydraulic pressure is selectively actuated by _L to select a predetermined shift speed, and that the shift to another shift speed is performed by changing the friction element to be actuated.

For this shift control, here is a computer for shift control.
14 and control valve 15 are provided. Computer
14 selectively turns on shift control shift solenoids 15a and 15b in the control valve 15 and selectively selects line pressure to various friction elements so that a corresponding shift stage is selected by a combination of ON and OFF of these shift solenoids. Supply P _L to control shift control. The shift control computer 14 also controls the line pressure control duty solenoid 16 in the control valve 15 by the drive duty D to control the line pressure P _L in the control valve 15 (the line pressure increases as the duty D increases). It shall be controlled as intended by the invention. A signal from the vehicle speed sensor 7 and a signal from the throttle sensor 8 are input to the computer 14 for the shift control and the line pressure control, respectively, and a signal from an input rotation sensor 17 for detecting the rotation speed _NT of the shaft 12 and Number of rotations of shaft 13
A signal from the output rotation sensor 18 for detecting N _O is input.

The computer 14 executes the control programs shown in FIGS. 3 to 5 to perform line pressure control and shift control.

First, the line pressure control program of FIG. 3 which is repeatedly executed by the timed interrupt will be described. In step 20, it is checked whether or not a gear change is in progress depending on whether a flag FLAG1 described later is 1 or not. As a result, if non-shifting is in progress, in step 21, the line pressure control solenoid drive duty D corresponding to the throttle opening TH is looked up from the non-shifting table data as shown by the solid line A in FIG.
Then, the drive duty D is output to the solenoid 16 to control the line pressure P _L to the normal value for non-shifting.

On the other hand, if the result of the above check is that shifting is in progress, in step 23,
A table lookup is performed for the line pressure control solenoid drive duty D corresponding to the throttle opening TH from the table data for gear shift as shown by the dotted line B in FIG. 6, which varies depending on the type of gear shift such as gear stage, upshift / downshift, etc. Then
Next, at step 24, it is checked whether or not the shift is an upshift that is particularly prone to a shift shock due to excessive line pressure. The drive duty D is output to the solenoid 16 as it is. on the other hand,
In the case of the upshift gear shift, in step 25, the throttle opening is calculated from the data of the line pressure control solenoid drive duty correction amount as shown in FIG. Read the line pressure control solenoid drive duty correction amount ΔD corresponding to TH. After that, in step 26, D + ΔD
Is output to the solenoid 16 to control the line pressure P _L to a value for shifting.

Next, the shift control and line pressure control solenoid drive duty correction amount control of FIG. 4 which are also repeatedly executed by the timed interrupt will be described. First, at step 30, it is determined whether FLAG1 is 1 or not, that is, whether or not the shift is in progress. If the gear is not checked, in step 31, the required shift speed corresponding to the combination of the vehicle speed V and the throttle opening TH is determined based on a predetermined normal shift pattern, and in step 32, the required shift speed is determined. It is checked whether or not the gear should be changed depending on whether or not the selected gear is different from the currently selected gear. If the gear shift is to be made as a result, FLAG1 = 1 is set at step 33 to indicate that gear shifting is being performed, and the solenoids 15a and 15b are turned on and off to shift to the required gear. When the gear shift is in progress, the steps 31 to 33 are skipped in the next control.

In step 34, it is checked whether or not the inertia phase has started, and in this check, the gear ratio represented by the input / output speed ratio N _T / N _O of the speed change gear mechanism 11 is set to the gear stage before the speed change. When the gear ratio starts to change from the corresponding gear ratio to the gear ratio corresponding to the gear after the gear shift, it is determined that the inertia phase has started. Then, here, the timer T ₁ is incremented (stepped) in step 35 until the inertia phase starts, and step 35 is skipped after the inertia phase starts, whereby the timer T ₁ measures the time before the inertia phase starts.

Then, in the following step 36, it is checked whether or not the inertia phase is in progress. In this check, it is determined that the inertia ratio is in progress while the gear ratio is changing from the gear ratio corresponding to the gear stage before the gear shift to the gear ratio corresponding to the gear stage after the gear shift. The timer T ₂ is incremented (stepped up) in step 37 during the inertia phase, and step 37 is skipped after the inertia phase, whereby the timer T ₂ measures the inertia phase time.

In the next step 38, it is checked whether or not the inertia phase is completed (shift completion is completed). If it is not completed, the program is ended as it is, and if it is completed, the step is completed.
At 39, the flag FLAG1 is reset to 0 corresponding to the end of the shift, and the flag FLAG2 for executing the learning control for correcting the data in the RAM shown in FIG. 7 is set to 1.

If the gear shifting is completed in this way and then the gear shifting is carried out, the control proceeds to step 40 through steps 30 to 32.
Since FLAG2 = 1 is set as described above, step 41 is selected and the previous data of the line pressure control solenoid drive duty correction amount ΔD shown in FIG. 7 is corrected and updated by the following learning control.

This step 41 is a subprogram as shown in FIG. 5, and here, first, at step 50, it is checked whether or not the time before the start of the inertia phase, which is the value of the timer T ₁ , exceeds the reference value T _1S . This is the timer for the line pressure control solenoid drive duty D + ΔD% during gear shifting.
The measurement times of T ₁ and T ₂ are as shown in FIG. 8, and when the line pressure control solenoid drive duty is extremely small such as α in the region where T ₁ > T _1S , the line pressure is Is extremely low, resulting in an out-of-shelf shift as shown by the chain line in FIG. 10, and the shift shock becomes extremely large as shown by α in FIG. 9 (β and γ in FIG. 9 are solenoid drive duty, respectively. Is an operation waveform when is the value indicated by the same sign in FIG. 8),
Even in the case of this out-of-shelf shifting, as described above, timer T ₂ ,
That is, since the inertia phase time is short, it is considered that the line pressure control solenoid drive duty D + ΔD% is too high as it is, and the line pressure control solenoid drive duty correction amount ΔD is corrected as described later to further reduce the line pressure. In order to avoid this, in step 50 above, the check result T ₁ > T _1S
If it is determined that the correction amount Δ is not reached in step 51, regardless of the value of the inertia phase time described later.
D is increased by 2% so as to promptly escape from the T ₁ > T _1S region, and then the process returns to step 41.

In the region T ₁ <T _1S , there are no such concerns, so step 52
Check the time measured by timer T ₂ , that is, the inertia phase time. When the inertia phase time T ₂ matches the target value (different for each type of shift and throttle opening) T _2S that corresponds to the line pressure that is preferable for preventing shift shock and reducing the life of the friction element, The data in the RAM for the correction amount ΔD in FIG. 7 is not changed and is used as it is for the line pressure control during the next shift. Then, when T ₂ > T _2S , the line pressure is too low and the life of the friction element is shortened due to the sliding of the friction element. Therefore, the execution of step 53 causes the RAM of the correction amount ΔD shown in FIG. The data in 0.2
% And used for line pressure control during the next shift. Therefore, at the time of the next line pressure control, the line pressure control solenoid drive duty D + ΔD is increased by 0.2% from the previous time and the line pressure can be increased by that amount, and the line pressure is brought close to an appropriate value to avoid the reduction of the life of the friction element. be able to. On the contrary, when T ₂ <T _2S , the line pressure is too high and a large shift shock is generated due to the excessive engagement capacity of the friction element. Therefore, the execution of step 54 causes RA of the correction amount ΔD in FIG.
The data in M is reduced by 0.2% and used for line pressure control during the next shift. Therefore, during the next line pressure control, the line pressure control solenoid drive duty D + ΔD can be reduced by 0.2% from the previous time to reduce the line pressure by that amount, and the line pressure can be brought close to an appropriate value to prevent a large shift shock. You can

After that, the process returns to step 42, FLAG2 is reset to 0, the values of the timers T ₁ and T ₂ are reset to 0, and the next measurement is awaited.

By repeating such an operation (learning control), the line pressure control solenoid drive duty correction amount ΔD is the line pressure control solenoid drive duty D + ΔD during the shift, and the line pressure is an appropriate value (irrespective of the individual difference of the automatic transmission or the change over time). Continue to correct the inertia phase time T ₂ to a value that makes it the target value T _2S ), and control the line pressure during shifting to an appropriate value that will not cause a reduction in the life of friction elements or a large shift shock under any circumstances. can do.

Moreover, according to the device of this example, when the inertia phase start time T ₁ exceeds the reference value T _1S , it is possible that the engagement of the friction element is too late and the out-of-shelf gear shift has occurred.
Since the line pressure solenoid drive duty correction amount ΔD is increased by a predetermined amount regardless of the inertia phase time T ₂ at the time of shifting when the inertia phase start time T ₁ is reached, the line pressure during shifting can be promptly increased, The out-of-shelf gear shift can be promptly avoided, and a large gear shift shock and a reduction in the life of the friction element can be reliably prevented.

Although the present invention has been described above based on the illustrated example, the present invention is not limited to the above-described example, and for example, learning control is performed not only in upshifting but also in downshift shifting and control for avoiding out-of-shelf shifting is performed. You may do it.

(Effects of the Invention) Thus, according to the line pressure control device of the present invention, when the gear shift is performed at such a low line pressure that the out-of-shelf gear shift is generated, the line pressure adjusting means is operated at the low line pressure. Regardless of the inertia phase time during gear shifting, the line pressure is controlled to increase by a predetermined amount, so the line pressure during gear shifting can be quickly raised, effectively avoiding out-of-shelf gear shifting, and avoiding large gear shift shocks. It is possible to reliably prevent the occurrence and the reduction of the life of the friction element.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a line pressure control device of the present invention, FIG. 2 is a control system diagram of an automobile power train showing an embodiment of the present invention device, and FIGS. 3 to 5 are shift control computers in the same example. 6 is a flow chart showing the line pressure control and shift control program of FIG. 6, FIG. 6 is a characteristic diagram of the line pressure control solenoid drive duty, and FIG. 7 is a momentary RAM regarding the correction amount of the duty.
8 is a diagram illustrating the data in FIG. 8, FIG. 8 is a diagram showing the relationship of the timer measurement time with respect to the line pressure control solenoid drive duty during shifting, and FIG. 9 is the solenoid drive duty of α, β, γ in FIG. FIG. 10 is a gear shift operation time chart showing a situation of occurrence of inertia phase during gear shift. 1 ... Electronically controlled fuel injection engine 2 ... Automatic transmission 3 ... Differential gear 4 ... Drive wheel 5 ... Engine control computer 6 ... Engine speed sensor 7 ... Vehicle speed sensor 8 ... Throttle sensor 9 ... Intake air amount sensor 10 …… Torque converter 11 …… Shift gear mechanism 14 …… Shift control computer 15 …… Control valves 15a, 15b …… Shift control shift solenoid 16 …… Line pressure control duty solenoid 17 …… Input Rotation sensor 18 ... Output rotation sensor

Claims (1)

[Claims] Claims: 1. Various friction elements of a speed change gear mechanism are selectively hydraulically actuated by line pressure to select a predetermined shift speed, and the friction element to be operated is changed to shift to another shift speed. An automatic transmission configured to slowly increase the hydraulic pressure of the hydraulic circuit by a stroke based on a back pressure corresponding to the line pressure of an accumulator provided in at least one hydraulic circuit that guides the line pressure to a friction element. An input rotation sensor and an output rotation sensor respectively detect an input rotation speed and an output rotation speed of the speed change gear mechanism, and an inertia phase time measuring means detects the input rotation speed and the output rotation speed between the input and output rotation speeds based on signals from these sensors. The inertial phase time is measured by measuring the time of the inertia phase when the gear ratio represented by the ratio changes. In a line pressure control device for controlling the line pressure during shifting so as to reach a target value for preventing a fast shock, an inertia phase is started from an instruction to change the friction element until the gear ratio starts to change. Inertia phase start time measuring means for measuring the previous time, and when the inertia phase start time exceeds a reference value for determining that it is an out-of-shelf shift that ends the inertia phase after the end of the accumulator stroke In addition, the line pressure adjusting means is provided with an out-of-shelf shift avoiding means for performing control for increasing the line pressure during shifting by a predetermined amount regardless of the inertia phase time, and Line pressure control device.